\chapter{Loop, Equipment Sizing and other Design Data}\label{loop-equipment-sizing-and-other-design-data}

The importance of correct equipment sizing is often ignored in discussions of building simulation methods. The lack of reliable, efficient and flexible sizing calculations can present a serious barrier to the adoption and acceptance of building simulation programs. This section describes the sizing methodology implemented in EnergyPlus. This method includes:

\begin{enumerate}
\def\labelenumi{\arabic{enumi}.}
\item
  A zone by zone heat balance load and air-flow calculation for multiple design days;
\item
  Significant user control with modest input requirements;
\item
  Zone, system and plant level calculations of design heating and cooling capacities and fluid flow rates;
\item
  Modular, component-specific sizing algorithms for each HVAC component.
\item
  Options for monitoring how the initial sizes operate over multiple design days and then making adjustments and repeating plant level calculations
\end{enumerate}
